This invention relates to the use of chiral diphosphines as optically active ligands for the preparation of diphosphino-metal complexes. The invention also pertains to the diphosphino-metal complexes comprising a chiral diphosphine as ligand and the asymmetric catalysis processes employing these complexes. The invention envisages more particularly the use of these diphosphino-metal complexes in asymmetric hydrogenation or isomerization processes for the synthesis of organic products of specified chirality.
Known in the prior art are different ligands used for the synthesis of diphosphino-metal complexes having catalytic properties in asymmetric hydrogenation. One can cite, e.g., the compound BINAP described by the Takasago company in European patent applications nos. 444 930 and 295 109, the compound MeOBIPHEP described by the Hoffmann-La Roche company in European patent application no. 398132 and PCT application No. WO 93/15090.
This invention relates to an (R) or (S) chiral diphosphine of formula (I): 
wherein R and R1, which can be identical or different, represent an optionally saturated C1-10 alkyl group, an optionally saturated C3-9 cycloalkyl group, a C5-10 aryl group, the groups being optionally substituted by a halogen, a hydroxy, a C1-5 alkoxy, an amino such as NH2, NHR4, N(R4)2, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, the alkyl, cycloalkyl, aryl groups optionally including one or more heteroatoms or R and R1 together represent an optionally saturated C2-6 substituted alkyl group, an optionally saturated C3-9 cycloalkyl group, a C5-10 aryl group, the cycloalkyl or aryl groups being optionally substituted by a C1-5 alkyl, a halogen, a hydroxy, a C1-5 alkoxy, an amino, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, the alkyl, cycloalkyl, aryl groups optionally including one or more heteroatoms, R2 and R3, which can be identical or different, represent an optionally saturated C3-8 cycloalkyl group, a C6-10 aryl group, the groups being optionally substituted by a halogen, a hydroxy, a C1-5 alkoxy, an amino, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, the cycloalkyl, aryl groups optionally including one or more heteroatoms, or R2 and R3 together form an optionally saturated C4-8 cyclic group, a C6-10 aryl group, the groups being carefully substituted by a halogen, a hydroxy, a C1-5 alkoxy, an amino, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, the cyclic and aryl groups optionally including one or more heteroatoms.